Phoenix development has been jointly led by Mingoo Seok and Scott Hanson, doctoral students in the Department of Electrical Engineering and Computer Science at the University of Michigan.
Hanson will present the design on 20 June at the Engineers' Symposium on VLSI Circuits run by the Institute of Electrical and Electronics Engineers.
Phoenix measures a modest one square millimetre, which the researchers admit is nothing special. However, the fact that its thin-film battery is the same size is a major achievement, according to the team.
"In most cases, batteries are much larger than the processors they power, drastically expanding the size and cost of the entire system," said David Blaauw, a professor in the Department of Electrical Engineering and Computer Science.
"For instance, the battery in a laptop computer is about 5,000 times larger than the processor and provides only a few hours of power."
The team hope that the breakthrough will help advance the development of cutting-edge sensor-based devices such as medical implants, environment monitors and surveillance equipment.
"Our system, including the battery, is projected to be 1,000 times smaller than the smallest known sensing system today," said Professor Blaauw. "It could allow for a host of new sensor applications."